Expansion bolt with unitary wedge assembly

ABSTRACT

A masonry anchor bolt is characterized by having a unitary wedge assembly which is preformed out of a blank of metal to comprise generally sleeve-like wedge members with a connecting bail between adjacent sides of the wedges so that the wedge assembly may be expanded into surrounding relation to an annular recess on the bolt surface, the connecting bail serving to maintain proper spacing and alignment of the wedge members both with respect to the recess and with respect to one another for selective automatic expansion of the wedge members along an inclined bearing surface into anchored engagement with the wall of the hole.

Aug. 7, 1973 1 EXPANSION BOLT WITH UNITARY WEDGE ASSEMBLY [75] Inventor:Lester Lerich, Lakewood, C010.

[73] Assignee: Wej-it Expansion Products, Inc.,

Broomfield, C010.

22 Filed: 11:11.4, 1970 211 App1.No.: 8,658

FOREIGN PATENTS OR APPLICATIONS 16,349 8/1908 Great Britain.... 85/77840,255 5/1952 Germany 85/78 913,838 6/1954 Germany 85/63 PrimaryExaminerMarion Parsons, Jr. Attorney-Reilly and Lewis 57 ABSTRACT Amasonry anchor bolt is characterized by having a unitary wedge assemblywhich is preformed out of a blank of metal to comprise generallysleeve-like wedge members with a connecting bail between adjacent sidesof the wedges so that the wedge assembly may be expanded intosurrounding relation to an annular recess on the bolt surface, theconnecting bail serving to maintain proper spacing and alignment of thewedge members both with respect to the recess and with respect to oneanother for selective automatic expansion of the wedge members along aninclined bearing surface into anchored engagement with the wall of thehole.

7 Claims, 7 Drawing Figures PATENTEU 3. 750.526

INVENTOR LESTER LER/CH /f' Maw ATTORNEYS EXPANSION BOLT WITH UNlTARYWEDGE ASSEMBLY This invention relates to a novel and improved expansionbolt and more particularly relates to a masonry anchor bolt of the typeprovided with anchoring elements assembled on the bolt which areautomatically displaceable into wedging engagement with the wall of ahole.

Masonry anchor bolts are customarily employed in fastening machinery,equipment and various members to masonry or rock structures. Typically,the bolt includes anchoring elements or wedge members which are disposedwithin a recess adjacent to the leading end of a bolt and are providedwith some form of expansion means. The latter will permit the anchoringelement normally to lie within the peripheral outline of the bolt sothat the bolt can be inserted into a hole of corresponding diameter tothe bolt; and when the bolt is advanced in the direction of withdrawal,or tightened, the expansion means will cooperate in displacing theanchoring elements along a forwardly divergent bearing surface into firmwedging engagement with the wall of the hole. Expansion bolts of thistype are set forth and dcscribed in United States Letters Pat. No.3,257,891, dated June 28, 1966, and No. 3,549,576, dated Apr. 22, 1969,both granted to the applicant of this invention. In each of the patentsreferred to there is specifically disclosed sleeve-like wedge memberswith springlike expansion elements between facing side edges of thewedge members and adjacent to the trailing ends thereof to encourageoutward radial expansion of the wedge members into firm anchoringengagement with the wall of the hole. For example, in the form shown inIt is another object of the present invention to provide in an expansionbolt for a unitary wedge assembly comprised ofa minimum number of partswhich can be prefabricated and assembled on a bolt with the wedgesmaintained in proper alignment both with respect to one another and withrespect to the bolt for rapid, automatic displacement into firm anchoredrelation to the wall of the hole.

It is a still further object of the present invention to provide for anovel and improved expansion bolt insertable into a blind holecorresponding in diameter to that of the bolt with a unitary wedgeassembly normally contained within the peripheral outline of the boltwhich is capable of rapid, automatic displacement into positive wedgingengagement with the wall of the hole.

It is an additional object of the present invention to provide in anexpansion bolt for a wedge assembly having improved expansion meanswhich are capable of maintaining proper alignment of the wedges on thebolt upon insertion into a hole as well as to effect accuratelypredictable movement and outward expansion of the wedge members intoanchored relation automatically upon tightening or advancement of thebolt in the direction of withdrawal from the hole.

In accordance with the present invention, a preferred form of masonryanchor bolt has two or more arcuate wedge members assembled insurrounding relation to a recess at the leading end of the bolt by aconnecting bail which serves to interconnect adjacent, longitudinal sideedges of the wedge members. Two adjacent side edges are not connected soas to permit expansion of FIGS. 1 to 4 of said US. Pat. No. 3,439,576the wedges are retained in assembled relation on the bolt by aconnecting bail, and expansion means are engageable at the oppositetrailing ends of the wedges to cause outward radial expansion of thewedge members into anchored engagement with the hole. Further, it isknown to employ sleeve-like wedge members which are assembled insurrounding relation to the recess with the aid of a temporary retainingband which is ruptured or parted under the force of expansion of thewedge members.

In accordance with the present invention, it is highly desirable tosimplify the fabrication and assembly of the wedge members on the boltand specifically in such a manner that the entire wedge assembly can bepreformed out of a single strip or blank of material with the necessarymeans for normally retaining the wedge members in assembled relation andfor urging the wedges radially and outwardly for expansion into anchoredengagement with the wall of the hole when the bolt is advanced in thedirection of withdrawal from the hole. Moreover, it is proposed that thewedge members be so interconnected as to be maintained in exactalignment under forward displacement and expansion as well as to affordpredictable movement of the wedges into anchored engagement so as toassure the maximum surface contact with the wall of the hole.

It is therefore an object of the present invention to provide in anexpansion bolt for novel and improved wedge assemblies which can besimply fabricated, rapidly assembled on the bolt and is capable ofpredictable movement into uniform wedging engagemnt with the wall of thehole.

the wedge members for assembly on the bolt and for subsequent outwardradial expansion of the wedges into anchored engagement with the wall ofthe hole about fulcrum points formed by the connecting bail at itsconnection to the side edges of the wedge members. Preferably, the bailis extended into notches formed in the sides of the wedges and itspoints of connection are selectively weakened to provide the necessaryflexibility of the wedges about selected points. In a preferred methodof fabrication, connected wedge sections are formed out ofa flat blankof metal with the outsides of the sections diverging forwardly to affordbetter surface contact in the hole; inner adjacent sides are selectivelynotched, preferably at the midsection as hereinbefore described, leavinga narrow connecting strip therebetween to define a connecting bailbetween the wedge sections. The strip is given additional resiliency orspringiness by work-hardening and may also be selectively weakened orthinned down at its points of connection to the wedge sections. The-flatwedge sec-- tions are then formed into substantially semi-circularconfiguration, and protrusions may be shaped in the middle of each wedgesection to aid in outward expansion of the wedges.

The completed, unitary wedge assembly is assembled over the annularrecess conventionally formed in the surface of the bolt simply byexpanding the free side edges of the wedges and slipping the assemblylaterally over the groove and compressing it down against the groove.Because of the memory of the spring-like bail, a slight spacing is leftbetween the wedges ,and the surface of the recess. However, as the boltis inserted into a hole substantially corresponding in size to that ofthe bolt, the wedges are compressed into the groove substantially withinthe peripheral outline of the bolt; under close-fitting engagement withthe wall of the hole, the leading ends of the wedges will be compressedor contracted ahead of the trailing endsso that the wedges are cockedsomewhat at the fulcrum of the points of interconnection of the ball ofthe wedges. Under expansion, the trailing ends, being cocked outwardly,will aid in outward expansion along the inclined bearing surface of thegroove, and the ball will serve the important function of urging thewedges outwardly against the hole while maintaining exact alignmentbetween the wedges.

The foregoing objects, advantages and features of the present inventionwill become more readily appreciated and understood from a detailedconsideration of the invention taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a side elevational view illusrating a preferred embodiment ofthe present invention inserted in a hole and prior to expansion of theunitary wedge assembly into anchored engagement with the hole.

FIG. 2 is a side elevational view similar to FIG. 1 but showing theunitary wedge assembly expanded into an chored relation to the wall ofthe hole.

FIG. 3 is a sectional view taken about lines 33 of FIG. 1.

FIG. 4 is a front view in elevation illustrating the formation of thepreferred form of unitary wedge assembly out of a blank of metal.

FIG. 5 is a cross-sectional view of the unitary wedge assembly takenabout lines 55 of FIG. 4.

FIG. 6 is a cross-sectional view of a modified form of unitary wedgeassembly; and

FIG. 7 is a sectional view taken about lines 77 of FIG. 6.

Referring in more detail to the drawings, there is illustrated in FIGS.1 to 5 a preferred form of expansion bolt 10 made up of an elongatedcylindrical shank member 12 having a threaded end section 13 at theexternal end of the shank. The opposite, leading end of the shank isprovided with an annular recess or groove 14 which is formed in theexternal surface of the bolt shank 12 to define a circumferentialshoulder portion 15 at its trailing end squared to the longitudinal axisof the bolt, a relatively deep groove surface 17 of uniform diameteradjacent to the shoulder portion verging into a forwardly divergent,inclined bearing surface 18 which terminates in a circular leading endsection 20 corresponding in diameter to the diameter of the bolt shank.

An important feature of the present invention resides in theconstruction and arrangement of a unitary or one-piece wedge assembly 24which is assembled on the bolt in surrounding relation to the groovesurface 17. The wedge assembly is broadly comprised of sleeve-like orgenerally semicircular wedge members 26 and each is provided with aleading end 27, a trailing end 29 and forwardly divergent. longitudinalside edges 29. A connecting bail 30 extends circumferentially betweentwo of the facing, longitudinal side edges 29 of the wedge members withopposite connecting ends 32 projecting into notches 33 formed in theadjacent sides of the wedges. The connecting bail 32 is dimensioned tobe of a length which will maintain a slight spacing between adjacentside surfaces 29 and preferably the bail is selectively thinned orweakened at its points of connection 32 to the wedges to define afulcrum for selective lateral expansion and contraction of the wedges ina manner to be described.

In the preferred form, the wedge members are of uniform thickness andare given a length and curvature corresponding to that of the groovedsurface 17. As il lustrated the wedge members are of arcuateconfiguration and of a width somewhat less than semi-circular to affordsufficient clearance or spacing for extension of the connecting bailbetween the wedges while permitting the wedges to be contractedsubstantially within the peripheral outline of the bolt shank 12 alongthe grooved surface 17.

The longitudinal side edges 29' of the wedge members opposite to theconnected edges 29 are of course free to expand; and to install thewedge assembly onto the bolt shank the wedges are laterally expanded toa sufficient degree to clear the external diameter of the groovedsurface portion 17 to permit the wedge assembly to be laterally advancedinto position within the groove. When the wedge assembly is placed overthe groove, it is contracted against the grooved surface portion, but ofcourse the memory of the connecting bail will cause the wedges to springoutwardly a very slight extent so that there is a slight spacing betweenthe inner surfaces of the wedges and the grooved surface. In addition,the diametrically opposed outward protrusions 36 are staked out of thegrooved surface portion 17; and when the wedge assembly is placed overthe groove and contracted against the groove surface, the protrusionsare aligned to project outwardly into the spaces between thelongitudinal side edges 29 and 29 so as to prevent rotation of the wedgeassembly on the bolt.

As illustrated in FIG. 2, the expansion bolt can be anchored in the holethrough the use of a washer 38 and nut 40 placed on the threaded end 13of the bolt; and in a conventional manner, inward threading ortightening of the nut against the washer will cause advancement of thebolt in the direction of withdrawal from the hole. The slight outwardspacing of the wedge assembly will cause the wedge members to engage theinner wall surface of the hole and to be displaced forwardly along thebearing surface 18 and at the same time to be radially expanded intofirm wedging engagement with the wall of the hole. To further aid inoutward expansion of the wedge members, the generally W-shaped ortriangular protrusions 25 will aid in establishing initial contact withthe wall surface and encourage forward displacement of the wedge membersalong the inclined bearing surface. In turn, the forwardly divergentsides 29' of the wedges will serve to establish a broad surface contactarea across the leading ends 28 as they are initially expanded along theinclined bearing surface; and in expansion the wedges are maintained inexact alignment with one another by the connecting bail. In thisrelation, the bail will serve to provide the needed flexibility foroutward radial expansion of the wedges but restrict relativelongitudinal shifting or displacement of the wedge members with respectto one another so as to effect predictable movement of the wedges intobalanced and uniform surface engagement with the wall of the hole.

In the preferred method of fabrication, the unitary wedge assembly 24 asdescribed is fabricated out of a flat blank of material represented at Min FIG. 5, which for example may be of spring steel composition. Theoutline of the wedge sections is stamped out of the material leaving aslight spacing as shown between adjacent side edges 29 together with thealigned notches 33 and a relatively thin, narrow connecting strip whichdefines the bail 30 located at the midsection of the wedge assembly. Thespring steel composition of the metal will give the wedge members somevery limited flexibility, and additional flexibility or resiliency isbuilt into the connecting strip 30 by work-hardening the strip, such as,by hammering or compressing into a relatively thin, narrow bandapproximating one-half the thickness of the wedge members. The strip isfurther thinned out or weakened at its connecting points 32 so thatbending of the wedge members will take place about the connection pointsbetween the bail and wedge members. The protrusions may be formed out ofthe thickness of the wedge sections, and the flat connected wedgesections may then be passed through a transfer die to form the wedgesinto circular configuration.

A modified form of wedge assembly is illustrated in FIG. '7 wherein thewedges 26' are formed out of a tapered blank so as to be given aforwardly tapered inner surface 44. In addition, opposite, free sides ofthe wedge members are selectively thinned or tapered as illustrated inFIG. 6 at 45 and 46 with a connecting bail 30' formed between adjacentsides in the manner described with reference to FIG. 5. In the modifiedform, the wedging action is the same as that described with respect tothe preferred form in effecting automatic expansion of the wedges intofirm positive engagement with the wall of the hole. In this relation,the wedge members may assume the configuration of a generallyshovel-shaped wedge as illustrated in United States Letters Pat. No.2,896,494 with the wedges assembled and interconnected by means of alateral interconnecting bail as described in the present invention. Thiscould be important in selected applications where more centralized orlocalized wedging action is preferred to the broadened surface contactobtained with the semicircular wedge described in the preferred form.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit of the invention.

What is claimed is:

1. In an expansion bolt having a shank portion adapted for insertioninto a bolt hole of a diameter substantially corresponding to that ofthe shank portion, said portion including an annular recess therein, thecombination therewith ofa wedge assembly comprising at least two wedgemembers dimensioned for disposition in the recess substantially withinthe peripheral outline of said shank portion, said wedge members eachhaving longitudinally extending side edges, and a connecting bailinterconnecting adjacent sides of the wedges, said bail being in theform of a flat band of reduced thickness with respect to said wedgemembers and extending between and flush with the external surfaces ofsaid wedge members and being relatively thin with respect to its widthso as to permit flexing of said wedge members in a direction radially ofsaid bolt while resisting independent longitudinal displacement of saidwedge members, and the points of connection of said bail to said wedgemembers being selectively weakened in a direction to define fulcrums forradial bending of said wedge members with respect to said connectingbail whereby to permit selective outward expansion of said wedges aboutsaid bail when said wedges are displaced forwardly along the inclinedbearing surface of said recess.

2. In an expansion bolt according to claim 1, said wedge members beingof a cross-sectional curvature corresponding to that of said recess, andsaid connecting bail maintaining said wedge members in closely spacedrelation to the surface of said groove prior to installation in thehole.

3. In an expansion bolt according to claim I, said connecting bail beingpreassembled in connected relation to said wedge members.

4. In an expansion bolt according to claim 1, said wedge members beingof uniform thickness with a cross-sectional curvature corresponding tothe curvature of the groove.

5. In an expansion bolt according to claim 1, said wedge memberstapering forwardly from the trailing toward the leading ends thereof.

6. In an expansion bolt according to claim 1, said wedge members eachtapering circumferentially toward the outer free side portions oppositeto the connected sides of said wedge members.

7. An expansion bolt comprising a shank portion insertable in a bolthole with the wall of the hole substantially corresponding in diameterto that of said shank portion, said shank portion provided with anannular groove on its external surface and adjacent to its leading endhaving a relatively deep grooved surface portion of uniform diametermerging into a forwardly divergent, inclined external bearing surface,and a unitary wedge assembly prefabricated out of a blank of metalcomprising a pair of wedge members normally disposed in surroundingrelation to the grooved surface portion substantially within theperipheral outline of said shank and a connecting strip extendingbetween the midsections of adjacent sides of said wedge members, saidconnecting strip being of reduced thickness with respect to said wedgemembers and extending flush with the external surfaces of said wedgemembers and spaced outwardly of the inner surfaces of said wedgemembers, said wedge members each tapering circumferentially away fromconnected sides toward outer free side portions opposite tothe connectedsides and being slidable forwardly along the external bearing surfaceinto anchored relation to the wall of the hole when said shank portionis advanced in the direction of withdrawal from the hole; said wedgemembers being formed with outwardly extending protrusions on theirexternal surfaces to aid in forward movement of said wedge members alongthe external bearing surface when said shank portion is advanced in thedirection of withdrawal from the hole; protrusions on the surface ofsaid groove to resist circumferential movement of said wedge memberswithin the groove; and tightening means at the end of said shank portionopposite to said annular groove operative to advance said shank in thedirection of withdrawal from the hole.

1. In an expansion bolt having a shank portion adapted for insertioninto a bolt hole of a diameter substantially corresponding to that ofthe shank portion, said portion including an annular recess therein, thecombination therewith of a wedge assembly comprising at least two wedgemembers dimensioned for disposition in the recess substantially withinthe peripheral outline of said shank portion, said wedge members eachhaving longitudinally extending side edges, and a connecting bailinterconnecting adjacent sides of the wedges, said bail being in theform of a flat band of reduced thickness with respect to said wedgemembers and extending between and flush with the external surfaces ofsaid wedge members and being relatively thin with respect to its widthso as to permit flexing of said wedge members in a direction radially ofsaid bolt while resisting independent longitudinal displacement of saidwedge members, and the points of connection of said bail to said wedgemembers being selectively weakened in a direction to define fulcrums forradial bending of said wedge members with respect to said connectingbail whereby to permit selective outward expansion of said wedges aboutsaid bail when said wedges are displaced forwardly along the inclinedbearing surface of said recess.
 2. In an expansion bolt according toclaim 1, said wedge members being of a cross-sectional curvaturecorresponding to that of said recess, and said connecting bailmaintaining said wedge members in closely spaced relation to the surfaceof said groove prior to installation in the hole.
 3. In an expansionbolt according to claim 1, said connecting bail being preassembled inconnected relation to said wedge members.
 4. In an expansion boltaccording to claim 1, said wedge members being of uniform thickness witha cross-sectional curvature corresponding to the curvature of thegroove.
 5. In an expansion bolt according to claim 1, said wedge memberstapering forwardly from the trailing toward the leading ends thereof. 6.In an expansion bolt according to claim 1, said wedge members eachtapering circumferentially toward the outer free side portions oppositeto the connected sides of said wedge members.
 7. An expansion boltcomprising a shank portion insertable in a bolt hole with the wall ofthe hole substantially corresponding in diameter to that of said shankportion, said shank portion provided with an annular groove on itsexternal surface and adjacent to its leading end having a relativelydeep grooved surface portion of uniform diameter merging into aforwardly divergent, inclined external bearing surface, and a unitarywedge assembly prefabricated out of a blank of metal comprising a pairof wedge members Normally disposed in surrounding relation to thegrooved surface portion substantially within the peripheral outline ofsaid shank and a connecting strip extending between the midsections ofadjacent sides of said wedge members, said connecting strip being ofreduced thickness with respect to said wedge members and extending flushwith the external surfaces of said wedge members and spaced outwardly ofthe inner surfaces of said wedge members, said wedge members eachtapering circumferentially away from connected sides toward outer freeside portions opposite to the connected sides and being slidableforwardly along the external bearing surface into anchored relation tothe wall of the hole when said shank portion is advanced in thedirection of withdrawal from the hole; said wedge members being formedwith outwardly extending protrusions on their external surfaces to aidin forward movement of said wedge members along the external bearingsurface when said shank portion is advanced in the direction ofwithdrawal from the hole; protrusions on the surface of said groove toresist circumferential movement of said wedge members within the groove;and tightening means at the end of said shank portion opposite to saidannular groove operative to advance said shank in the direction ofwithdrawal from the hole.